The invention relates to a process for accelerating the hardening of cement with fibre-reinforced and cement-bound plates or profiles.
It is a well known fact that for accelerating hardening of cement the so-called carbonization process can be used as has been applied in the concrete and ceramic industry.
The essential feature of said process lies in having Ca/OH.sub.2 compound present in a significant proportion in cement mortars and cement admixed with water, which is converted to limestone under the influence of CO.sub.2 gas. This process--namely carbonization--is taking place very quickly and the resulting bonds interconnecting the molecules of limestone are so strong that concrete strength may reach about 35 to 50% of the strength of concrete at the age of 28 days in just 5 to 30 minutes, in spite of the fact that the hydration process has not yet begun.
The carbonization process and mode of application are detailed in U.S. Pat. Nos. 109,669; 3,468,993; 4,362,679 and 4,093,690, as well as in GB-PS No. 1,460,284; Swedish Patent No. 110,792 and Swiss Patent No. 584,666.
From the patents enumerated it becomes obvious, in so far as:
in general, the material containing cement and intended to be carbonized is arranged in a space which can be closed,
in said space, by introducing CO.sub.2 gas, overpressure is established while CO.sub.2 gas penetrates into the pores of the cement-containing material stored therein,
in the space which can be closed, first of all, a vacuum is produced by exhausting the air, thereafter CO.sub.2 gas is introduced, as a consequence, CO.sub.2 gas easily penetrates into the pores of the cement-containing material stored therein.
However, known and used technical solutions serving for the realization of the carbonization process involves a not negligible drawback; in so far as manipulation of the cement-bound fibrous material requires a closed space, the construction thereof is most expensive.
A further problem lies in efforts to obtain a properly airproof sealing; that is a most complex task, even for those skilled in art.